Conventionally, as an image forming device, the constitution to control the amount of toner to be supplied to a developer bottle on the basis of the concentration of the toner in a developer bottle has been publicly known (for example, refer to Japanese Patent Application Laid-Open No. 5-6090).
In addition, as other image forming device, the constitution to control the supply amount of the toner to a developer bottle in response to the number of printing dots (a dot count value) has been publicly known (for example, refer to Japanese Patent Application Laid-Open No. 5-40408).